Mine go in cycles sometimes too. I can go for a couple of months when they aren't quite as severe and then a month when I have more episodes than usual and they are worse. I have kept diaries looking for triggers; what I ate, things I smelt, not wearing my sunglasses, sounds. I haven't come up with anything. It is really frustrating.
I'm sorry you can't take Relpax, I love it. It works for me better than anything else I've tried. I'm also on Inderal LA twice a day. It's supposed to keep them from happening or lower the intensity. I tried Topamax and Zonegran. I hated the Topamax and the Zonegran didn't work very well either. The Inderal seems to work better so far, it's usually for prescribed high blood pressure, but my neurologist wanted me to try it. I haven't been on it for very long, so we'll see. Have you tried something like this? Maybe you can tolerate it.
Also, something I wanted to share. I just remembered this because it's new to me. I'm taking a stress management class in school. I stress like crazy and know it can and does contribute to my headaches and migraines. We did this thing called a power nap last week. I went in to class that day feeling crappy and came out feeling better. The effects lasted all day. Then on Friday, I was at the point of going to hit the clinic and I remembered the power nap, which I have on CD. I put it in and did it. It takes about 15-20 minutes to do. By the time I was done, I didn't need to go. It was still there, but the roaring and pounding had subsided so that I could care for it well enough at home. I will ask my professor tomorrow if there is a web site for it and share. I was skeptical, but now am amazed and can't wait to learn some of the other techniques. Anything to be able to stay home.